1. Field of the Invention
The present invention relates to a product (including a machine, a manufacture, and a composition of matter) and a process (including a simple process and a production process). In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, and a power storage device, to a method for driving the same, and to a method for manufacturing the same. In particular, one embodiment of the present invention relates to a semiconductor device including an oxide semiconductor, a display device including an oxide semiconductor, or a light-emitting device including an oxide semiconductor.
2. Description of the Related Art
In recent years, flat panel displays such as liquid crystal displays (LCDs) have been widespread. In each of pixels provided in the row direction and the column direction in a display device such as a flat panel display, for example, a transistor serving as a switching element, a liquid crystal element electrically connected to the transistor, and a capacitor connected to the liquid crystal element in parallel are provided.
As a semiconductor material for forming a semiconductor film of the transistor, a silicon semiconductor such as amorphous silicon or polysilicon (polycrystalline silicon) is generally used.
Metal oxides having semiconductor characteristics (hereinafter referred to as oxide semiconductors) can be used for semiconductor films in transistors. For example, techniques for forming transistors using zinc oxide or an In—Ga—Zn-based oxide semiconductor are disclosed (see Patent Documents 1 and 2).